# HOW FAST?

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Define rate of reaction
change in concentration of reactants/ products per unit time
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What is meant by the initial rate?
rate at start where gradient steepest
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How can rate be measured?
Acids/bases - Change in pH with pH probe/ titrations// gas vol produced per unit time/ rat elf colour change
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Define the rate equation
illustrates relationship between rate of reaction and initial concentration of reactants
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What is the rate equation?
r = k [A]m [B]n
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What is k?
rate constant, constant that links rate of reaction with the conc of reactants raised to the power of their order
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What is the order of a reaction?
power to which the conc of reactants are raised to in the rate equation
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describe a zero order conc vs time graph
straight line, half life decreases
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describe a first order conc vs time graph
curve, constant half life - half life independent of the change in conc
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describe a second order conc vs time graph
curve, half life increases
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Define half life
the time taken for the concentration of reactants in a reaction to decrease by half
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What is the rate determining step?
the slowest stop in a reaction mechanism which determines the overall rate of reaction
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describe a zero order rate vs conc graph
conc does not affect rate, straight horizontal line
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describe a firs order rate vs conc graph
straight line through origin, conc is directly prop to rate
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describe a second order rate vs conc graph
rate is prop to change in conc-.squared / curved positive line
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How does temperature effect k?
rate of reaction will always increase at higher temps, cause k to increase
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Describe the effect temperature has on k using a Maxy B distribution graph
more molecules all have energy greater than or equal to activation / more successful collisions/ exponential relationship
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Describe the rate determining step
reactants involved in the RDS are present in the rate equation/ any step that occurs after will not affect rate/ can be predicted/ use to find order
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what is an intermediate species?
of a multistep reaction, a molecule/ ions generated in one step as a product but used win another as a reactant
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What evidence would there be that a reaction takes place in more than one step?
elements in chemical equation that are not in the rate equation/ orders in rate reaction differ to those in the chemical equation
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## Other cards in this set

### Card 2

#### Front

What is meant by the initial rate?

#### Back

rate at start where gradient steepest

### Card 3

#### Front

How can rate be measured?

### Card 4

#### Front

Define the rate equation

### Card 5

#### Front

What is the rate equation?